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[Wittsend]

2ml of phosphoric acid is a very low concentration - would hardly do anything even in a small volume of water.

There's a higher concentration in Coca-Cola 

So maybe the numbers are wrong ^^^

You can readily buy phosphoric acid on eBay at various concentrations - I wouldn't go for anything less than 15%.
I bought 35% and you can easily and safely dilute it down to what suits your work.

Phosphoric acid is the core ingredient to those rust treatments like Jenolite (can you still get that) and the Machine Mart stuff.
These products are recognised by their pink colour.

It's more a case of finding a treatment (or recipe) that you find (over the years) does the best job for you.

I've always used a phosphoric acid treatment since boyhood. It works well and it's quite quick acting - no prolonged soaking - although for really well rested up stuff that you can't wire brush off the worst - soaking and leaving might be the best method

I find the phosphoric acid treatment gives a good prep for (etch) primer and then undercoat etc. etc.

You can also use phosphoric acid in an electrolytic cell which deep cleans/de-rusts an object as I posted ^^^ in reply #7

 

PS
It seems Jenolite is alive and well 
I recommend reading the link in reply #6 

[2286]

Not really cheap but I have found washing powder works well on cleaning up galvanised and gunk.

Soak as long as possible.

[Ken]

Yes, I found the formula on line. I thought I’d said in my original post that the phosphoric acid is used to modify the Ph which ( from memory should be 2 to 2.5) I checked using litmus papers.
The tannic acid is doing the converting.
I

[w3526602]

Hi,

My father once pointed out that shovels used for moving "cow exhaust" are usually very shiny.

I have read (but not recently) that the canals in Denmark are covered in old barges loaded with pig "zorst". I pondered on loading a scrap oil tanker with this effluent, and importing it into UK.

Why?

To salvage the "fumes", to be used to power vehicles, and then spread the now  sweet smelling "stuff" on UK fields as a fertiliser. The tanker would retain it's scrap value. Everybody would win.

602

[2286]

Shiny metal and power as a by product

Top marks 602

Re Cow shovel, the key could be movement as opposed to what it is moving in, as when static it eats metal.

[diffwhine]

I agree - anybody with a yard tractor and scraper will attest to that.